Alexander Mauskop, M.D., says most Americans don't get enough magnesium from their diets. Some of the healthy volunteers in his study, published in Headache and described above, had low serum ionized magnesium but their total magnesium levels were normal. This, researchers suggest, "supports the notion that magnesium deficiency could be an important factor in the etiology of headaches." Low ionized magnesium levels are caused by poor absorption, a magnesium-deficient diet and, perhaps most importantly, from excessive magnesium loss in urine. Stress contributes to this magnesium loss and, ironically, low magnesium status increases vulnerability to stress. Certain illnesses such as diabetes predispose to magnesium loss through urine.

The U.S. RDA for magnesium is 350 mg/day for men and 280 mg/day for women. The richest sources of this mineral are whole grains, nuts, seeds, legumes, cocoa and green leafy vegetables.